1. Field of the Invention
The present invention relates in general to emission control systems mounted in a motor vehicle, and more particularly to a vapor diffusing device which effectively diffuses, into the open air, the vapor which is inevitably drained from a carbon canister mounted in an engine room of the motor vehicle, when the engine stops.
2. Description of the Prior Art
Hitherto, carbon canisters have been widely used in motor vehicles for reasons of antipollution, which contain activated carbon and adsorb evaporated gases or vapor from a fuel tank thereby to prevent emission of the vapor into the open air. However, due to the inherent construction of the conventional carbon canisters, part of the vapor led into the canister is forced to discharge into the open air through a purge air inlet formed in the bottom of the canister, particularly at the time when the engine stops. In view of this phenomenon, some of the carbon canisters are equipped with a drain hose which extends from the bottom of the canister to a vapor diffusing device mounted in an engine room of the motor vehicle.
In order to clarify the task of the present invention, one conventional vapor diffusing device will be outlined with reference to FIG. 15.
Referring to the drawing, there is shown a conventional vapor diffusing device 100 fluidly connected with a carbon canister 10, which are mounted in an engine room E of a motor vehicle.
The carbon canister 10 is of a conventional one which comprises a cylindrical case 12 containing therein activated carbon and filters in a known manner. The carbon canister 10 shown in the drawing is mounted through a bracket 14 to a radiator core support 16 which constitutes a front panel member of the engine room E. Designated by numerals 18, 20 and 22 are respectively an evaporated gas tube from a fuel tank (not shown), a vacuum line from an intake manifold (not shown) and a purge air tube from the intake manifold. A drain hose 24 extends from a purge air inlet formed in the bottom of the canister 10 and leads to the vapor diffusing device 100.
The vapor diffusing device 100 comprises a front side channel member 26 and a hood ridge panel 28 which are assembled together to form an elongate space A therebetween. It is to be noted that the space A extends longitudinally from a front portion of the vehicle toward a passenger room of the same. Designated by numeral 24a is a connector used for connecting the leading end of the drain hose 24 to the channel member 26.
Vapors given off by the fuel in the fuel tank are led into the carbon canister where they are adsorbed. When the engine is restarted, fresh air is drawn through the activated carbon. The incoming fresh air purges or removes the vapors from the activated carbon and carries them into the intake manifold to be burned in the combustion chamber. As is described hereinabove, however, at the time when the engine stops, part of the vapors remaining in the canister is forced to discharge through the drain hose 24 into the space A of the vapor diffusing device 100. The vapors then flow in and along the space A, as shown by the arrow B, toward a longitudinal one perforated end of the device 100 where the vapors are diffused to the open air.
However, the disclosed conventional vapor diffusing device 100 is so constructed and arranged that the perforated end thereof is positioned near the passenger room of the vehicle. Accordingly, foul smelling vapors are often discharged into the passenger compartment.